The foundation conditions of rocks and soils are an important consideration for determining how surface construction loads are transmitted into the ground safely and for the lifespan of the project.

What are foundation conditions?

Preparation of ground prior to building foundation.

The foundation is the interface of some form of construction and the ground. Design of the foundations takes into consideration a number of factors including the response of the ground to the stresses produced by the construction. The behaviour, or 'condition', of the ground may be assessed by in situ and/or laboratory tests during a typical site investigation. This dataset highlights common factors to consider when planning for a site investigation or land-suitability assessment.

The main considerations are:

strength or bearing capacity

settlement (compressibility) and differential settlement

volume change of the ground due to climatic conditions

subsidence due to natural voids beneath the foundation, leading to ground failure

Classification

The primary classifiers give a qualitative assessment of the likely ground conditions for foundations. This is based on characteristics including bearing capacity (strength), compressibility, rate of consolidation and the variability of the ground conditions for each unit. A special case for construction above mapped coal seams is also given, and this is also relevant for units that contain coal seams. In these cases this is one of the subsets.